1. Field of the Invention
The present invention pertains to a process for the hydrogenation of an aromatics-containing feedstock in which process a specific catalyst suitable for the hydrogenation of aromatics is applied.
2. Prior Art
Typically, fuels such as diesel fuels and kerosene are commonly prepared by cracking or hydrocracking high boiling feedstocks, such as vacuum gas oils or residues, with the aid of a cracking catalyst or a hydrocracking catalyst, and separating the resulting product into fractions if so required. However, in general, the fraction thus obtained is suitable neither for use as a fuel as such, nor for addition to a “pool”. This is because the fuel has to meet certain specifications, including, in particular, specifications with respect to the aromatics content. Because it is both environmentally advisable and increasingly legally required, it will become ever more necessary to reduce the aromatics content of fuels such as diesel oils and kerosene.
A common method to reduce the aromatics content of hydrocarbon feedstocks is to contact said feedstocks in the presence of a hydrogen-containing gas with a hydrogenation catalyst to effect aromatics hydrogenation. Aromatics hydrogenation catalysts have been described extensively in the art.
For example, U.S. Pat. No. 3,703,461 describes a catalyst to be used in the hydrogenation of aromatics which comprises one or more of the metals of platinum or palladium on a carrier consisting of silica-alumina dispersed in alumina binder. An alumina binder amount of 50–90 wt. % is preferred, with an alumina binder amount of 60–80 wt. % being most preferred. The catalysts used in the Examples of this reference all contain platinum as the only Group VIII noble metal.
Further, JP 09225304 discloses a catalyst to be used for the hydrogenation of aromatics comprising platinum on a carrier consisting of silica-alumina dispersed in an alumina binder. The carrier preferably comprises 50–95 wt. % of alumina binder and most preferably 60–90 wt. % of alumina binder.
M. Vaarkamp et al. (Engelhard), Prepr.-Am. Chem. Soc., Div. Pet. Chem. 43(1), 77–79 (1998) discloses a catalyst to be used for the hydrogenation of aromatics comprising a combination of platinum and palladium on various inorganic supports. These supports are selected from alumina, silica, silica-alumina, and magnesia.
EP 0947248 describes a catalyst to be used in the hydrogenation of aromatics which comprises a combination of platinum and palladium on a support comprising silica-alumina and about 7 wt. % of an alumina binder. The silica-alumina comprises 60–80 wt. % of alumina.
PCT/NL98/00090 describes a catalyst to be used, int. al., in the hydrogenation of aromatics which comprises a combination of platinum and palladium on a silica-alumina carrier. The silica-alumina may comprise, e.g., 10 wt. % of alumina and 90 wt. % of silica. In a comparative example this publication describes the use of a catalyst containing a combination of platinum and palladium on a carrier comprising silica-alumina and 30 wt. % of an alumina binder, wherein the silica-alumina contains 13 wt. % of alumina, in the hydrogenation of a feedstock containing 8 wt. % of aromatics. In view of the low aromatics content of the feedstock and the fact that it is a comparative example, the skilled person would not consider this catalyst suitable for use in the hydrogenation of aromatics.
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